Size coding of alternative responses is sufficient to induce a potentiation effect with manipulable objects

Area of Science:

• Cognitive Psychology
• Motor Control
• Perception-Action Coupling

Background:

• Object perception typically primes corresponding motor actions, like power grips for large objects and precision grips for small ones.
• The embodied view posits this priming arises from motor representations of grasping behaviors.
• A competing size-coding hypothesis suggests overlap in size codes for objects and responses explains this effect.

Purpose of the Study:

• To test the size-coding hypothesis against the embodied view of action priming.
• To investigate whether size compatibility between perceived objects and response actions influences reaction times.
• To determine the role of response device size and effector size in size coding of responses.

Main Methods:

• Four experiments were conducted, manipulating object type (power-grip vs. precision-grip) and response characteristics.
• Experiment 1 removed the grasping component, using horizontal switches (small/large) and specific hand/digit responses.
• Subsequent experiments further isolated the contributions of switch size and effector size.

Main Results:

• Reaction times were shorter when object size codes matched response size codes (e.g., small object with small switch).
• This size compatibility effect was observed regardless of whether grasping was involved.
• Both the size of the response switch and, to some extent, the effector part (hand/digit) contributed to size coding.

Conclusions:

• The findings support the size-coding hypothesis, suggesting that size compatibility, not motor representations, drives grasping potentiation.
• This indicates that response actions are coded based on size, extending the principles of the Theory of Event Coding.
• The study challenges embodied views by highlighting the role of abstract size codes in perception-action links.